Since the beginning of wire, and later wireless, communications, an implicit goal of communications systems has always been to bring remotely located participants as close together as possible. This is also the goal of a traditional teleconferencing system. Ideally, the effect obtained in good communications should be one of "being there."
A conventional teleconferencing system comprises two or more stations which are illustratively connected via the public switched telephone network. At each station, there is a camera for transmitting a video image to a remote station. There is also a microphone for picking up sound and forming an audio signal for transmission to the remote station. The typical teleconferencing station also includes a video monitor for receiving a video signal from the remote station to produce an image of a conferee at the remote station and a speaker for receiving an audio signal from the remote station.
In most teleconferencing systems, the video camera at a sending station is an NTSC camera which has a limited field of view. This camera forms an image on a conventional NTSC monitor at a receiving station remotely located relative to the sending station. One problem with this arrangement is that the conventional NTSC monitor is relatively small-sized. When the number of teleconference participants at the sending-end of a teleconference is larger than one, the image of each participant occupies a small portion of a small viewing area on the receiving monitor. As a result it becomes difficult for viewers at the receiving end of such an image to pick up non-verbal cues from the speaker's body and face. Indeed, in many cases it is often difficult to discern at the receiving-end who of the many participants at the sending-end is actually speaking.
U.S. Pat. 4,890,314 discloses a teleconferencing station which solves one aspect of this problem. In particular, in accordance with U.S. Pat. 4,890,314, a transmitting teleconferencing station includes, for example, first and second cameras which are specially arranged to have contiguous fields of view over a range of distances from the cameras. The two cameras produce first and second video signals corresponding to first and second sub-images. At the receiving teleconferencing station, the two sub-images are displayed using a unique display device so that the two sub-images merge contiguously to form a single high resolution image. The cameras at the transmitting station collectively have a larger field of view than a single camera would have, and, at the receiving-end, a much larger image is formed than would be the case if a conventional NTSC monitor were to be utilized.
Another problem associated with the conventional teleconferencing station is that a teleconference participant has no control over the view of a remote location that is displayed on the local monitor. Typically, at a sending teleconferencing station, whether the imaging device is a single NTSC camera or a combination of cameras as described in U.S. Pat. No. 4,890,314, there is a fixed field of view which is transmitted to a receiving participant. The receiving participant only sees whatever object or persons happen to be in the fixed field of view. Of course, a remote camera can be gimbal mounted and controlled by the viewer. However, in this case, there can only be a single locally available view of the remote station so that each of a plurality of viewers cannot choose their own view of the remote station.
Accordingly, it is an object of the present invention to provide a television system which provides a local viewer with a locally controllable view of a remote location. In particular, it is an object of the present invention to provide a system in which a local viewer can select an arbitrary and continuously variable section of a remote wide angle field of view for display on a local monitor.
It is a further object of the invention to provide a television system in which a plurality of viewers at different locations can each select his/her own view of a remote location. Specifically, it is an object of the invention to provide a television system in which each of a plurality of viewers can choose his/her own section of a remote wide angle field of view for display on his/her own monitor.
The inventive television system is especially useful in teleconferencing applications.